Nils emel norstrom



PATENTED JAN. 19, 1904.

N. E. NORSTROM TELEPHONE EXCHANGE.

APPLICATION FILED NOV. 23, 1900.

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No. 749,824. PATENTED JAN. 19, 1904,

N. E. NORSTROM, E TELEPHONE EXCHANGE.

APPLICATION FILED NOV. 23, 1900. N0 MODEL.

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APPLICATION FILED NOV. 23, 1900.

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No. 749,824. Patented January 19, 1904.

1 UNITED STATES P TENT OFFIC NILS EMEL NORSTROM, or cHicAeo; ILLINOIS, AssieNoR or TWO-THIRDS TO JOHN ANDERSON, or SALINA, KANSAS, AND M. E. RICHARDSON, or sriza nve, KANSAS. a

TELEPHONE-EXCHANGE.

SPECIFICATION forming part of Letters Patent No. 749,824, dated January 19, 1904. A

Application filed November 23,1900. Serial No. 37,475. (No'modeL) ing mechanisms at the local stations.

illustrated diagrammatically and will be read- TO 11/71/017? i y q In the said drawings, M is aframework on Be it known that I, NILs EMEL NORSTROM, a whichare secured the magnets A and B and citizen of the United States of America, and a to which are also pivoted their armature-leresident of Chicago, county of Cook, and State vers A. and B. Also pivoted on the frame 5 of Illinois, have invented certain new and use- M,and preferably at the same pivoting-point ful'Improvcments in Telephone-Exchanges,,.of as the lever A, is a ratchet-quadrant M, on which the following is a specification. which is a contact-arm M In its normal po- My invention relates to telephone-exchanges sition thepointer M rests on a contact-point of the character in which a series of tele J and in the path of the contact-arm M when 10 phone-stationsare connected by a party line moved there are a series of other contactto a central office, and has for its object .im} points. J one of which is connected to the llIOVGIIlGIltSiIl such exchanges. e. normal. contact-point J by a short wire J".

, One of the particular features of the pres- The connected contact-point J 2 is in each staent application is the provision of devices that tion a different distance from the normal con- I 5 will prevent a person at one of said stations tact-point. For example, at telephone-stafrom listening to conversation carried on be tion No. 2 the connection is to the second contWeen two other parties. For example, in. tact-point, at telephone-station No. 3 it is to the exchanges usingparty-lines as they are at the third contact-point, and so on. On the present arranged a'person located at one of armature-leverfAis a pawl A arranged to 20 the exchanges can by keeping his receiver re' move the ratchet-quadrant M when the magmoved from its hook listen to any conversa net A is energized. The relationship of the tions that may be carried on by any other parratchet to the contact-points is such that upon ties on the line and at the same time he is althe first movement of the contact-arm it is ways in position to be called from'the central moved to a blank position between the first 2 5 office. I overcome this objection to partycontact-point and the normal contact-point. lines by arranging the switching mechanism At the next movementit will reach the first at the several stations so that the connections contact-point and at each subsequent movecannot be controlled in this way by a person ment the next succeeding contact-points. On at one of the stations and cannot be controlled the armature-lever B there is a holding-pawl 50 at all -by him except by tampering withthe B and from the armature-lever there is a mechanism of his switch. As the switching, pin projecting beyond that engages a small mechanism at-eac'h station in this class of depin A in the moving pawl A". These parts are vices is always inclosed Within the telephoneso arranged that when the magnet B is charbox, is locked up, and presumed to be intergized; both of said pawls are lifted from en- 3 5 fered with only by person authorized from gagement with the ratchet and the contactthe central'office, it'will be evident that the arm M is permitted to return to its'normal opportunities for tampering with the mechposition. Also located at each station are a 5 anism are reduced to a minimum. 1 pair of magnets Cand E. The magnetsC and 1n the accompanying drawings, Figure 1 is E are polarized, so that when a current is sent 40 a diagram of the mechanism at the, central of through them, in one direction the magneto ficeand that of one local station, and Fig. 2 is energized, whilewhen the current is sent is a diagram showing two additional telethrough in the opposite direction the magnet 9 phone-stations that are connected to the cen- E is energized. These magnets'are provided tral oflice by the line-wires 50 and 100. Fig. with armatures C and E and contact-points 45 3 is an elevation of the receiver-hook and the adjacent thereto, as shown in the drawings.

associated parts. Figs. 4 is a section on line There are also at each local station the ordi- 4: of Fig. 3, and Fig. 5 is a plan of the switchnary apparatus of atelephone station, which is ily understood. Secured to the quadrant M i is an arm M so arranged that when the contact-arm M is at its normal position the arm M will press a contact-spring 54 against the contact-point 53. When the contact-arm M has been moved one step, the connection between 53 and 54 is broken. At the central office there is the usual apparatus the nature of which'and its connections will become apparent in a description of the operation.

Assuming that subscriber at telephone No. 2 wishes to talk with the subscriber at telephone No. 4, he first removes his receiver,when the hook H rises, making electrical connection to a contact-spring 27 This contact between the hook and spring 27-ismade during the rising movement of the hook and is released just before the hook reaches its elevated position. A current then flows from the battery X at central office to 20, D, 22, 21, D, 23, 24, 50, 25 of telephone No.2 to 26, 27, H, 28, 100, 29, 30, 31, X. This operatesthe drop D at the central office to call the operator. By

pressing key 33 the operator is then in telephonic connection with the subscriber at telephone No. 2 and can inquire what subscriber is wanted. The talking-circuit is from the induction-coil at the central office to K, R,-32, 33, 100, 23, H, K, R, 36, M', M, M", 25, 50, Kat the central office. The subscriber then hangs up his receiver until called by'the operator at central or depresses the hook H by hand, when the operator presses the key 31 and the current flows as follows: Ground at central office to 37, 38, 31, X, 20, 39," 40, 34, 29, 100, 28 of each station to 41, C, E, 42 to ground at the several local stations. This operates the magnets C, closing the armatures G to the contact-points 44, when in each station a;

current flows to Y, 43, C, 44, 45, 46, 47, 48, 49, 51, A', 52, Y. This adv'anceseach contact-arm M one step and is repeated until the Contact arms are all on the second contact p'oint, when the operator turns her generator-crank, and the current flows as follows: Gr, 56, 29, 100, 28, H, 57,Q, 58, J,J, J M M 25,50, G. This calls the subscriber who originally called the central office and who again removes the receiver, thereby breaking the connection between 47 and 48, so that the magnet A cannot again be energized, and consequently the contact-arm M cannot be moved beyond the contact-point J to which is connected the wire J. The operator at central then presses the key 31 as before, advancing all of the other contact-arms to the fourth contact-point,when she again turns her generator-crank, calling the subscriber at telephone No. 4. The talking-circuit between the two telephones thus connected is as'follows: Kof No. 2, to R, 36, J, M M, M 25, 50,'to 25 of telephone-station No. 4, to -M M, M J 36, R, K, 35, H, 28,

' 100, back to 28of telephone-station N0. 2, to

'H, 35, K. By pressing the key 33 the operator 31, X, 39, 61, 62, 37, to ground at the central oflice. This reverses the direction of the current through the magnets C and E, .thereby energizing the magnet E and moving the armature E into connection with the contactpoint 63, when a current flows as follows at each local station: Y, 43, E, 63, 64, B, 52, Y. This releases the pawls from the quadrant and permits the contact-arms M to return to their normal position.

' Referring back to the local circuit through the magnet A, if a subscriber should attempt to prevent his contact-arm from moving to one of the contact-points which is not connected to the normal contact-point the first closure of the key 31, which energizes magnet C, and thereby closes the circuit through magnet A, will flow as follows: Y, 43, C, 44, 45, 53,54, 55, 51, A, 52, Y. As soon as the contact-arm ismoved one step the connection is opened between 53 and 54, and consequently the contact-arm of the subscriber who has removed his receiver is left with said contactarm at'a blank connection, in which case he is not in telephonic connection with any line.

What I'claim is r 1. The combination with the switching mechanism of a telephone-station comprising a series of contact-points, a contact-arm therefor, and a magnet 'for moving said contactarm, of a battery and connections for operating said magnet, a circuit-breaking device in said connection, a. receiver-hook arranged to close said device when in one position and to open itwhen in another position, a branch connection around said circuit-breaking device arranged to permitof a single movement of said contact-arm, a central oflice, connections from the central office to the station, and means whereby said magnet may be operated from said central office.

anism a movement limited to one step.

Signed at Chicago, Illinois, this 30th day of October, 1900.

' N. EMEL NORSTROM.

Witnesses:

, CHAS. O. HATCH,

CASPER L. REDFIELD.

IIO 

